Spoked solenoid armature for an electromechanical valve

Abstract

In a high pressure fuel injector 10, 56 for direct injection of fuel into an internal combustion engine, the armature 28, 54 has a hub member 70 connected by means of spokes 40, 82 to a concentric ring member 42. This construction reduces the amount of magnetic material in the armature hence reduces magnetic losses and speeds up the actuation times. Spaces between the spokes allow for the passage of fluid from one side of the armature to the other during actuation.

I claim: 
     
       1. An electromechanical fuel injector having a solenoid actuating system for opening and closing a valve having a cylindrical solenoid frame member having an inner tubular member and an outer tubular member radially displaced from each other and joined together at a one end forming a closed end; coil means located in said outer tubular member surrounding said inner tubular member and extending substantially the full depth of said frame member from the open end to the closed end forming a stator member wherein each of said tubular members form outer and inner concentric pole piece members, respectively, at said open end; a valve means; elongated needle means having a valve member at one end and extending axially from said valve seat means toward said stator; and bias means located in said inner tubular member of said solenoid member to bias said elongated needle means against said valve seat; the electromechanical fuel injector comprising: a magnetic disk means having a central aperture and substantially enclosing said coil means at said open end, said disk is connected to said outer concentric pole piece member providing a magnetic path to magnetically locate said outer concentric pole piece member adjacent to the inner diameter of said central aperture; and armature means secured to said elongated needle means at the end opposite said valve member, said armature means being a spoked member with a central hub and a concentric ring connected to said hub by means of a plurality of spokes having passageways therebetween, the axial cross section of said armature means from said hub to said ring being "J" shaped forming inner and outer working gap surfaces on said hub and said ring, respectively, with said hub surface axially displaced from said ring surface, said inner working gap surface of said hub being magnetically coupled to said inner concentric pole piece member and said outer working gap surface of said ring being magnetically coupled to said magnetically relocated outer concentric pole piece member providing dual working gaps, said armature means being magnetically attracted to said pole piece members when said coil means is actuated to axially displace said valve member from said valve seat. 
     
     
       2. An electromechanical fuel injector having a solenoid actuating system for opening and closing the valve according to claim 1 wherein the leading edge and the trailing edge of the cross section of said spokes connecting said ring to said hub in the axial direction are rounded. 
     
     
       3. An electromechanical fuel injector having a solenoid actuating system for opening and closing the valve according to claim 2 wherein a central portion of said hub additionally supports said bias means. 
     
     
       4. An electromechanical fuel injector having a solenoid actuating system for opening and closing the valve according to claim 1 wherein said ring of said armature means has an outer diameter larger than said central aperture of said disk and said hub has a diameter substantially equal to the diameter of said inner concentric pole member. 
     
     
       5. An electromechanical fuel injector having a solenoid actuating system for opening and closing the valve according to claim 1 wherein said spokes are blended into said ring in a smooth transition surface formed by a substantial curved surface. 
     
     
       6. An electromechanical fuel injector having a solenoid actuating system for opening and closing the valve according to claim 1 wherein said hub of said armature means has a length shorter in the axial direction than said concentric ring of said armature means. 
     
     
       7. An electromechanical fuel injector having a solenoid actuating system for opening and closing the valve according to claim 6 wherein said concentric ring of said armature means has an outer diameter larger than said central aperture of said disk and said hub has a diameter substantially equal to the diameter of said inner concentric pole piece member with said ring and hub surfaces radially displaced by means of circumferential trough across said spokes and said spokes are blended into said ring in a smooth transition surface formed by a substantial curved surface.